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  Atomic Theory — Infoplease.com
The Chemistry of Biology—Atomic Theory - The Chemistry of Biology Atomic Theory The Chemistry of Biology Introduction Atomic Theory Chemical...
Theories of the Universe: Bohr's Atomic Theory - Theories of the Universe Bohr's Atomic Theory Theories of the Universe That Old Quantum Theory...
Atomic Theory - Atomic Theory That all elemental bodies consist of aggregations of atoms, not united fortuitously,...
www.infoplease.com /ipa/A0905226.html   (1109 words)

 Atomic theory - Wikipedia, the free encyclopedia
In chemistry and physics, atomic theory is a theory of the nature of matter, which states that matter is composed of discrete units called atoms, as opposed to antiquated beliefs that matter could be divided into any arbitrarily small quantity.
Atomic theory began thousands of years ago as a philosophical concept, and in the 19th century achieved widespread scientific acceptance thanks to discoveries in the field of stoichiometry.
This, coupled with the fact that hydrogen—being the lightest element ever found—had an atomic mass of 1, led him to conclude hydrogen nuclei were singular particles, a basic consituent of all atomic nuclei: the proton.
en.wikipedia.org /wiki/Atomic_theory   (2854 words)

 Atomic Theory   (Site not responding. Last check: 2007-11-04)
The Atomic Spectra of an element are the lines which are present at characteristic wavelengths in the light emitted from an electric arc between electrodes of that element.
The atomic volume of an element is the relative atomic mass of the element divided by is density.
The atomic weight of an element is its relative atomic mass, which is the ratio of the average mass per atom of the naturally occurring form of an element to one twelfth (i.e.
www.ucc.ie /academic/chem/dolchem/html/dict/atom.html   (1217 words)

 Fundamentals of Atomic Theory   (Site not responding. Last check: 2007-11-04)
Dalton’s theory can be used to explain the carbon monoxide/dioxide situation: it takes twice as much oxygen to form carbon dioxide because each carbon atom needs two oxygen atoms whereas each carbon atom only needs one oxygen atom to make carbon monoxide.
Atomic weight—the average mass of the atoms of an element taking into account the masses of the various isotopes and their relative abundance.
Quantum mechanics is a theory that describes the behavior of the electrons in an atom.
www.chemprofessor.com /atomic.htm   (2429 words)

 Atomic Theory
As Democritus definitively recorded it, this atomic theory is applied in three realms: the natural/metaphysical, the microcosmic human, and the ethical.
On a societal level, atomic theory proposed that a system of law was necessary and that each individual should make a positive contribution to the community.
Atomic theory had a hard time at the hands of the thinkers who answered its suppositions.
ccat.sas.upenn.edu /~fiorile/atomic7.html   (905 words)

 Atomic Theory
Early atomic theory stated that the characteristics of an object are determined by the shape of its atoms.
Using the ideas of kinetic theory, the idea that the properties of a gas are due to the motion of the atoms that compose it, Loschmidt calculated the mean free path of an atom based on diffusion rates.
Atomic theory is the field of physics that describes the characteristics and properties of atoms that make up matter.
zebu.uoregon.edu /~js/21st_century_science/lectures/lec05.html   (2672 words)

 Atomic Theory
Atomic weight is the weight of an atom expressed in atomic mass units (amu).
Scientists determine the atomic weight of an element with more than one isotope by averaging the weights of all the isotopes in the proportions in which they occur in nature.
This value is an average for the two isotopes chlorine 35 (atomic weight 34.96885) and chlorine 37 (atomic weight 36.96590) in their natural proportions.
www.laughtergenealogy.com /bin/histprof/misc/atomic.html   (3920 words)

 Atomic Theory | World of Physics
Atomic theory is the description of atoms, the smallest units of elements.
Although atomic theory was abandoned for this long period, scientific experimentation, especially in chemistry, flourished.
The energy depended on the atomic number for that element, and the atomic number corresponded to the number of positive charges in the nucleus.
www.bookrags.com /research/atomic-theory-wop   (3908 words)

 Atomic Theory
Nevertheless, the rise of ether theories to explain the transmission of light and electromagnetic forces through apparently empty space postponed for many decades the general reacceptance of the concept of atoms.
These attempts to describe the basic constituents of matter in the familiar language of fluid mechanics were at least atomic theories in contrast to the anti-atomistic movement at the end of the 19th century in Germany under the influence of Ernst Mach and Wilhelm Ostwald.
The atomic number determines the chemical properties of the atom, and in alpha decay a helium nucleus, whose atomic number is 2, is emitted from the radioactive nucleus, leaving one whose atomic number is reduced by 2.
abyss.uoregon.edu /~js/glossary/atomic_theory.html   (946 words)

 Atomic Theory
The objective of this lesson is for students to become familiar with the historic and scientific development of atomic theory.
Students will be informed that in their studies of atomic theory, they will discover that scientific theory also requires previous levels of theorization.
The report should contain a general summary of atomic theory, it should name the individual they have selected as the most significant, and should clearly state reason(s) that defend their selection.
www.gsu.edu /~mstjrh/atomictheory.html   (551 words)

 Basic Atomic Theory for Chemistry
Dalton's atomic theory immediately led to the realization that although atoms are far too small to be studied directly, their relative masses can be estimated by observing the weights of elements that combine to form similar compounds.
An alternative way of examining the behavior of individual atomic particles became evident in 1899, when J.J. Thomson, whose work on "cathode rays" had revealed that the atoms has internal components of its own, showed that the charged particles resulting from their break-up could be deflected by externally-applied magnetic and electrostatic fields.
The unified atomic mass unit is defined as 1/12 of the mass of one atom of carbon-12.
www.chem1.com /acad/webtext/intro/AT.html   (5372 words)

 Atomic Theory   (Site not responding. Last check: 2007-11-04)
These philosophers did not have a method to verify the theory and it was not pursued for many centuries.
The theory reappeared in the early 19th century as an explanation for several laws that had been established in the previous century when chemists had begun carefully measuring the mass of reactants and products.
Of course nowadays the atomic theory is fundamental to the physical sciences.
www.tannerm.com /atom_theory.htm   (320 words)

 Atomic theory Summary
Atomic theory," wrote Bernard Pullman, "is the most important and enduring legacy bequeathed by antiquity." Indeed, this the atomic theory provides a brilliant example of pure speculation which develops into a universally accepted scientific theory.
In chemistry and physics, atomic theory is a theory of the nature of matter.
Atomic theory: The gold foil experiment Top: Expected results: alpha particles passing through the plum pudding model of the atom undisturbed.
www.bookrags.com /Atomic_theory   (336 words)

 Fourth dimension atomic theory
The atomic functions within the atom are continuously modified at an energy level, which is directly proportional to the atomic mass of the atom.
Because the Dovada research team works with a fourth dimension atomic model, many of the physical constants, similar to the Fine Structure Constant, are now very easily defined from first principles directly from the atoms spiral galaxy and orbital acceleration vectors and the reason for their very existence is now fully documented and understood.
Indeed our models encompass existing theories and expand them into areas that were previously poorly explained or considered under the banner of phenomena, the modern atomic model theory needs to be enhanced, to remove this over hanging banner of phenomena.
www.dovada.com /research/technology.htm   (1363 words)

 Atomic Structure
This law states that "the properties of the elements are periodic functions of atomic number." The periodic table is a chart which categorizes elements by "groups" and "periods." All elements are ordered by their atomic number.
Atomic mass is measured in Atomic Mass Units where 1amu = (1/12)mass of carbon measured in grams.
Atomic orbitals are known as s, p, d, and f orbitals.
www.shodor.org /unchem/basic/atom   (1742 words)

 Theory - Wikipedia, the free encyclopedia
In science, a theory is a proposed description, explanation, or model of the manner of interaction of a set of natural phenomena, capable of predicting future occurrences or observations of the same kind, and capable of being tested through experiment or otherwise falsified through empirical observation.
A theory is a logically self-consistent model or framework for describing the behavior of a related set of natural or social phenomena.
In this sense, a theory is a systematic and formalized expression of all previous observations that is predictive, logical and testable.
en.wikipedia.org /wiki/Theory   (2715 words)

 Atomic Theory Summary
One very early theory was that everything was made of four elements - Earth, Air, Fire, and Water - in various combinations.
Atomic weight is the weighted average mass number of all the naturally occuring isotopes of an element.
The atomic weights listed on the periodic table are all calculated this way, except for the very heavy nuclei (atomic number > 82) with no stable natural isotopes.
www.dbooth.net /mhs/chem/atomictheory.html   (910 words)

 Dalton's Atomic Theory
The ancient Greek philosophers had talked about atoms, but Dalton's theory was different in that it had the weight of careful chemical measurements behind it.
Although a number of chemists were quickly convinced of the truth of the theory, it took about a half century for the opposition to die down, or perhaps I should say die off.
A model focuses on describing what the atoms are like, whereas the theory not only talks about what the atoms are like but how they interact with one another and so forth.
dl.clackamas.cc.or.us /ch104-04/dalton's.htm   (549 words)

 Atomic Theory I
Atoms of different elements are distinguished from each other by their number of protons (the number of protons is constant for all atoms of a single element; the number of neutrons and electrons can vary under some circumstances).
To identify this important characteristic of atoms, the term atomic number (z) is used to describe the number of protons in an atom.
The weight of an atom is roughly determined by the total number of protons and neutrons in the atom.
www.visionlearning.com /library/module_viewer.php?mid=50   (868 words)

 The Atomic Theory
Subtracting the atomic number from the atomic mass number gives the number of neutrons in the nucleus.
Isotopes are atoms of the same element (i.e., they have the same number of protons, or the same atomic number) which have a different number of neutrons in the nucleus.
The average atomic mass of an element takes into account the relative proportions of its isotopes found in nature.
library.thinkquest.org /27948/bohr.html?tqskip1=1   (461 words)

 Atomic Theory II
The atomic number (z) is the same in both isotopes; however the atomic mass increases by one in deuterium as the atom is made heavier by the extra neutron.
Key to Bohr's theory was the fact that the electron could only "jump" and "fall" to precise energy levels, thus emitting a limited spectrum of light.
Under Bohr's theory, the maximum capacity of the first (or innermost) electron shell is two electrons.
www.visionlearning.com /library/module_viewer.php?mid=51   (1036 words)

 Chapter 5 - Atomic Structure and the Periodic Table
Atomic mass of element X = (mass A)(fraction of A) + (mass B)(fraction of B) +.
The atomic mass of X-72 is 72.0093 amu and the atomic mass of X-73 is 72.9984 amu.
the atomic mass of Z-84 is 83.9873 amu and the atomic mass of Z-86 is 85.9930 amu.
pages.prodigy.net /anderhan/Ch5AtomicTheory.html   (2020 words)

 Physics 30: Atomic Physics - Atomic Theory
Use the atomic number of an element to determine the number of protons in a nucleus.
Use the atomic mass number and the atomic number to determine the number of neutrons in the nucleus of an atom.
Explain that quantum theory helps to explain the photoelectric effect, the Compton effect, and other important physical principles which earlier theories did not account for adequately.
www.sasked.gov.sk.ca /docs/physics/u8a3phy.html   (1168 words)

 atom: Development of Atomic Theory
The atomic theory, which holds that matter is composed of tiny, indivisible particles in constant motion, was proposed in the 5th cent.
Interest in the atomic theory was revived during the 18th cent.
The development of quantum mechanics during the 1920s resulted in a satisfactory explanation for all phenomena related to the role of electrons in atoms and all aspects of their associated spectra.
www.factmonster.com /ce6/sci/A0856763.html   (640 words)

 CHEMystery: Atoms and Molecules: Dalton's Atomic Theory   (Site not responding. Last check: 2007-11-04)
The atomic number or number of protons determine what element is. For example, every element in the universe with 10 protons is neon, and every element with 79 protons is gold.
The atomic masses of isotopes are different because the number of neutrons in the atom are different.
Isotopes are represented with a mass number as superscript and atomic number as subscript.
library.thinkquest.org /3659/atommole/atoms.html   (534 words)

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